Method and apparatus for protecting alpha catalytically acting or purifying materialagainst contact poisons



Jan. 12, 1932. G, K, E H, STAMPE 1,840,611

METHOD AND APPARATUS FOR PROTEGTING A CATALYTICALLY ACTING ORPURIFYING MATERIAL AGAINST CONTACT POISONS Filed Nov.5, 1929 IQ/@Mfg if wwf) Patented Jan. i2, 1932 wh-* i STAMPE, F LBECK, GERBIANY, ASSIGNOR TO OTTO HEINRICH DRGER, 0F LBECK, GERMANY GERHARD KARL EMIL HEINRICH METHOD AND APPARATUS FOR PROTECTING A CATALYTICALLY ACTING 0R PURIFY- ING MATERIAL AGAINST CONTACT POISONS; i

Y Application sied November 5, 1929, serial No.

Air purifying materials, for` instance, such used in canisters for breathing implements are known to act in a catalytic way. Such purifying materialshave the peculiarity, that they are inclined to become ineffective by cer- A tain contact poisons contained in the air to be purified. Therefore they must be protected by depriving the stream of air before p entering` the purifying material from the contact poisons contained therein. Steam or water vapor is a contact poison, for instance,

s for the catalyst for oxydizing carbon monoxide, known as hop'calite. The air passing :l s. l the water vapor by a dryino' the catalyst is usually prepared by removing layer, for instance chloride of calcium. QMoreover, it is known to producey by the aid of the contact poisons a warning material adapted, for invstance by irritating the nose, the lungs or the A throat to indicate thus the deterioration of the catalyst.

Contrary to this procedure the new invention stipulates that a current of air containing contact poisons, which is to be purilied, is subjected to one or more substances, which destroy the contact poisons before the air enters the catalytically acting materiaL-which substances change or partly change. these poisons into a warning substance retained by the duly working catalyst. IWith a material catalytically oxidizing carbon oxide, for which water vapor is a contact poison, the method is carried out by arranging in front of the air purifying material a drying layer, the drying effect of which consists both in removing' the water vapor and in simulta' neously producing a warning substance. Such a drying layer may consist by way of example of calcium carbide or another light metal carbide which in contact with water vapor develops acetylene or a similar hydrocarbon. Thus the air when entering the canister first comes into Contact with the drying layer. According to this invention this drying material (such as calcium chloride, for instance) takes the water vapor from the air and at the same time gives off a hydrocarbon (acetylene in this case). This hydrocarbon is oxydized while the catalyst is working properly. When the catalyst is breaking 405,047, and in Germany November 19, 192s.

down, however, the hydrocarbon passes the canister and warns the person workingunder the mask by the smell or bythe irritating effect on the breathing passages.

shown in vertical section to tion is applied.

In this box the air purifying material, for instance a catalyst oxydizing Vcarbon oxide, is designated with c. The direction of the stream of air is indicated by arrows. l Before meeting the purifying material c the air passes through a layer Z2, for instance calcium which the inven- Icarbide. The two outer layers a and d are formed of calcium chloride. As a and d are only for the protection'of the other layers and not of importance for this invention inthe following explanation the lcanister will be supposed to contain only the layers ZJ and 0. For the catalyst c water vapor is a contact poison which is always contained in the air to be purified.' The air containing vcarbon oxide and water vapor enters the canister from below in the direction ofthe arrow. In the ll yer of calcium carbide I) `the water vapor is held back,` because the calcium carbide-is a very' excellent drying means. Vhen combining with water it produces acetylene. Thus only carbon oxide vand acetylene enter together with4 the air the layer c'. These impurities are destroyed by a catalytic oxydation, so that only non-poisonous air leaves the upper end of the canister. When, however, the drying layer b begins to be exhausted, it is no longer able to turn allthe water vapor intoacetylene.` I The consequence is, that air passes, fromb into c, which besides acetylene contain-s stillsome water vapor, which latter is yapt to make the purifying material c ineffective. y

By absorbing the water'vapor the catalyst loses at the same time the vc'apacity'to oxydize thetotal amount of 4carbon oxide and acetylene entering it. Consequently the air escaping fromthe cartridge is no morefully purified, but' still contains acetylene besides carbon oxide. AThe carbon oxide is, it is true, inodorous, `but thepimpure acetylene being generated by the technical calcium carbide is noticed byz'the smell. The wearer of the In the drawing a breathing canister is* breathing mask Will thus be notified of the exhaust or th-e beginning of the exhaust of the purifying material.

The layer el of the calcium chloride has the'purpose to prevent the entrance of Water Vapor from the upper end of the canister, and the layer a of calcium chloride may be used, if thereis the possibility that the amount of Water in the air is -very large. It only re- 1., moves part of the vapor before the air enters the layer I) to prevent the amount of developed acetylene from becoming too large and the catalyst c from -enduring too heavy a strain. The layer a may be left avvayvwithpg, out disturbing the action of the here described device. When thel protective layer Z is exhausted'or when no protection is used at the top of thel canister it may happen that some Water vapor enters the catalyst c and affects M a the latter to a Vslight degree, then there Will be no indication of an exhaust Which in fact in such case is not necessary. Y

Such exhaust, however, Will b-eindicated,

if the catalyzing material is made ineffective i not by Water vaporbut by other means, either during storage r during operation of the canister.

I claim 1. In an air purifying cartridge containing tto a layer of catalytic purifying material, a layer of dehydrating material disposed on the inlet side of said catalytic purifying material, said de-hydrating material being adapted to combine With the moisture of the contami- J nated airvto form a Warning gas capable of rial when active but adapted to pass through the same When` exhausted, said layer reacting tofform the Warning 'gas being disposed on the inlet side of the layer of `catalytic purifying material.

, 3.y In an air purifying cartridge containing f Abe removed by said catalytic purifying mateis a contact poison disposed in the path of moisture containing contaminated air to be purified, a layer of material containing 'a light metal carbide also disposed in the path ofthe airto be purified and positioned on the inlet side ofthe aforesaid layer o-f catalyticmaterial.

5. A purifying cartridge comprising a layer of light metal carbide, in the VpathV of moisture containing contaminated air to be purified, and a lay-er o-f catalytic purifying material also disposed'in said path on-the outlet side of the carbide layer, the reaction product of the moisture in the contaminated air andthe carbide being oxidized in the presencek of said catalytic material When active but passing therethrough When the same is exhausted. n

6. Device as claimed in claim 5 wherein the light metal carbide is calcium carbide. j

7. Method ofpurifying air containing moisture which comprises passingthe same in contact with a dehydrating agent, and then passingv it in contact With a purifying catalyst, the dehydrating'agent being of sucha nature that at least a portion thereof reacts with the moisture of the. contaminated air to said catalyst when active. v Y

8. Method as claimed in claim 7 Where-in the reaction product of themoisture inthe contaminated air and the dehydrating agent constitutes a Warning gas.

In testimony whereof I have signed my name to this speciiication.

GERHARD KARL EMIL HEINRICH STAMPE.

forma product removable in the presence of a layer of catalytic purifying material for 'i which Water is a contact poison, dehydrating allayer of catalytic material for oxidizing carbon monoxide and for which Water vapor 'means in the path of the contaminated air to 

